Back-pedaling brake.



No. 708,228v

E. G. HOFFMANN. BACK PEDALING BRAKE (No Model.)

(Application led Muy 10,1900.)

Patented sept. 2, |9072.

3 SheetsfSheet I.

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No. 708,223, Patented' sept. 2, |902.

E fa. HUFFMAMN.l BACK PEDALING BRAKE.

(Application mea my 1o, 1900.)

(No Model.) 3 Sheet-Sheet 2.

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nu 708,228. Patented sept. 2,1902.

LG. HoFFMAnN. BACK PEDLING BRAKE.

'Application med Hay 10, 1900.)

(No Model) 3 Sheets- Sheet 3:

UNITED STATES PATENT OFFICE.

ERNST GUSTAV HOFFMANN, OF CHELMSFORD, ENGLAND.

BACK-PEDALING BRAKE.

SPECIFICATION forming part of Letters Patent No. 7 08,228, datedSeptember 2, 1902.

Application filed May 10, 1900. Serial No.l6,14'7. (No model.)

To all whom t may concern."

Be it known that I, ERNST GUsTAv HOFF- MANN, a subject of the GermanEmperor, residing at Chelmsford, in the county of Essex, England, haveinvented a certain new and usefulBack-Pedaling Brake, of which thefollowing is a specification.

My invention relates to certain improvements in the form of driving andbrake mechanism frequently employed for cycles and usually known asfree-wheel mechanism, one of the objects of my invention being toproduce mechanism which'is self-contained, so that the wheel-hubcarrying same may be applied to existing wheels, the braking portion ofthe device necessitating no connection with the frame of the vehicle, asis the case with some forms of these devices.

In carrying out my invention I cause the driving and the braking actionto take place between the same members, which in the construction I amabout to describe as an illustration are the sprocket-wheel orequivalent part driven from the pedals and a surface carried by the hub.

I have illustrated in the accompanying drawings the form which Iconsider at the present time the most suitable forV carrying myinvention into eect, though it will be understood that there are variousother ways in which the parts may be arranged and the requisitemovements obtained.

In the drawings, Figure 1 is a longitudinal elevation, one-half being insection,ofa wheelhub having my invention applied thereto. Fig. 2 is asimilar view, but with the sprocketwheel and attached parts removed.Fig. 3 is a part elevation and part section of the sprocket-wheel andspring-controlled bearing detached. Fig. 4 is an end elevation of thesprocket-wheel. Fig. 5 is a part elevation and part section of theball-cage which effects the driving. Fig. 6 is an end elevation of same.Fig. 7 is a part elevation and part section of the brake-cam andconnected parts which effeet the braking; and Fig. 8 is a face view ofthe disk portion of same to 'show the cam-surfaces, the other partsbeing partially removed.

In the drawings, 1 is theusual spindle carrying the foot-step 2, screwedup to Washer 3 against the frame-fork 4, which is held against thewasher 5l, Which abuts against a shoulder 5 on the spindle. On thespindle is a sleeve 6, having two conical faces forming a race for aseries of balls 7, the adj Listing-cones of which consist of rings 8 8,adjustable by means of a lock-nut 9 of some suitable type. Such ringsand lock-nut are contained in the cylindrical hub-body 10, and theadjustment obtained by the lock-nut for the ball-bearing described iscommunicated by means of the sleeve 11 to similar cone-rings 8 S at theother end of the hub, the balls 7 bearing on which run on adouble-cone-faced sleeve 12 on the spindle. The outer ring of the lasttwo rings 8 abuts against a ring 13, having a conical face, which isscrewed to an extension 14 of the hub 10. The hub has also an enlargedor expanded extension 15, carrying a double cone 16, which in the caseshown is formed in one with the hub, but which may be formed ofphosphor-bronze or some other suitable metal or be faced with leather inorder to al low it to grip a correspondingly-shaped surface formed inthersprocket or other wheel 17. This sprocket-Wheel consists of achambered ring having a race for a series of balls 18, such race havinga double-coned face, While the balls bear upon a conical sleeve 19,capable of sliding on the extension 14, such part 19 being preventedfrom slipping away from the balls when the sprocket-wheel is detached,as shown in Fig. 3, by a spring-Wire 20, sprung into a groove in the endof same and the projection of which above its surface is suflicient tohold the parts together. A coil-spring 21 seats in the recess of the hubformed between the extensions 14 15 and tends to press the sleeve 19forward. Inside the chambered portion of the sprocket-wheel are a seriesof cam-surfaces 22, and projecting i'nto spaces between such cams arepins 23. Bearing on the conical face ofthe ring 13 and between same andthe cam-surfaces 22 is a series of balls 24, held in a cage 25, into ahole in which is turned one end of a coilspring 50, as seen in Fig. 5,the other end of which is similarly turned into a hole in the chamberedportion of the sprocket, as shown at 26 in Fig.`3. The cage is providedon its IOO outer periphery with three spiral or angular grooves 27, asshown in Figs. 5 and G, with which grooves engage the pins Screwed uponthe other end of the spindle 1 is a nut 29, having avwasher 30 betweenit and the other fork 4, which in turn is held against a washer 31,which is screwed to the spindle and abuts against an extremely powerfulspring 32, contained in a box 33, surrounding the spindle. To this boxis screwed a disk 34, (see Figs. 7 and 8,) having a series ofcam-surfaces 35 formed in a groove in same, such cam-surfaces graduallydecreasing in depth from one end to the other. A ball 36 rests on eachcam-surface and is held in place by a cage 37, as shown in Fig. 7, suchcage consisting of a ring having openings therein, the edges of whichare burred over or otherwise, so as to prevent the largest diameter ofthe ball passing through. This cage is retained in the disk by a splitring of wire 39, which is sprung into grooves partly formed in the diskand partly in the edge of the cage, as shown. The balls when at thehighest points of the cam-surfaces project and are then in contact withthe surface 40 of the sprocket-wheel.

It will be seen that upon removing one of the nuts at the ends of thespindle the latter can be -unscrewed from the washer3l and withdrawn, sothat all the parts maybe removed separately from the hub, as shown inFigs. 3, 5, and 7.

The position shown in Fig. l is that of driving. In this case anincreased or a forward movement of thesprocket-wheel over that of thewheel-hub will cause the balls 24 to rise up the cam-surfaces 22radially; but as they also travel upon the conical surface 13 themovement is changed as the balls reach their highest point to alongitudinal or lateral motion,which forces the cage 25 to the left,partly rotates the spring 50, and drives the conical surfaces of thesprocket-wheel 17 into engagement with the part 16 of the hub, so thatboth rotate together. This motion of the sprocketwheel coming intoengagement with the hub is a spiral one or similar to that of ahighpitch screw-thread, the radial and lateral movements of the combinedballs, which together produce the spiral mot-ion, imparting the samemotion to the sprocket, the cage following such motion the balls beginto grip between the cam-surfaces, while the spring 50 causes the ballsguided by the cage to be always ready for action or for forwardengagement. As soon as the hub runs faster than the sprocket,which isthe position when the pedals are held stationary by the feet, the spring21 forces the sleeve 19, ball-bearing sprocketwheel, and cage to theright, so that the reverse spiral movement takes place. The sprocket 17is accordingly withdrawn from contact with part 16, and the hub andwheel run freely, the sprocket being thus brought with its surface 40into contact with the balls 36 of the disk 34,which Icall the brake-cam,

but without any action on same save that of rotating the balls. Vthenbraking is desired, the sprocket is rotated, necessarily in the reversedirection, with the result that the movement of same acting on the balls36 causes them to travel toward the highest point of the cam-surfaces35, so that the sprocket is moved back laterally into contact again withpart 16 (which, it will be seen, acts both for driving and braking) andunited firmly therewith,so that the hub and sprocket again come intocontact and the sprocket acts with a retarding eect upon the hub, theaction being controlled by the pedals, with the result that the brakingaction is analogous to back-pedaling in an ordinary machine, being doneby holding back upon the pedals by the feet in the usual way, which thusholds the sprocket, with the result that the friction of same againstthe balls of the disk causes the latter in their rotation to rise uptheir camsurfaces and force the sprocket laterally back against theforwardly-rotating hub portion, so that such hub portion and wheel havetheir momentum checked to an extent which is regulated by the pressureplaced by the foot upon the pedals. It will be understood that the disk34 for this purpose should be rigidly Xed upon the spindle l in order togive the necessary xed abutment to receive the thrust of the balls 36,and this is practically the case in the arrangement described; but Ihave found it necessary in providing means for allowing the cycle orvehicle to be moved backward to avoid a possible engagement of thesprocket with the balls of the brake-cams whereby the pressure maybecome excessive in a longitudinal direction upon the disk 34. This istherefore provided for by the spring 32, which is suiiciently strong tohold the disk in position as an abutment firmly enough for brakingpurposes,but which will allow it to yield slightly to prevent it or anyof the parts breaking by an excess of press'ure exerted between the diskand the sprocket,as the balls may, if the disk 34 yields suiiciently,rise up the length of each camsurface and drop into the next one or maycause the disk 34 and box 33 torotate backwardly around the spindle 1 atthe same speed as the hub and wheel.

It will be understood that the spring 32 is suiciently strong to holdthe disk 34 against any pressure used in back-pedaling, so that duringthis action the disk is practically one with the spindle, and that suchdisk only yields to allow the wheel to travel backwardly, as suchbackward movement of the wheel starts by causinga jamming of the ballsagainst the surface 40 of the sprocket, which would prevent the wheelfrom rotating backwardly and probably fracture the parts if such ayielding means were not provided. In considering this relief ,action ofspring 32 it should be realized that in back-pedaling the disk 34 actspractically as a fixed part and IOO IIO

does not yield bythe spring coming into action, as in back-pedaling,because the force applied has first to overcome the forward motion ofthe 1otatingwheel, and hence no pressure which can be exerted in thisway is'sufficient to cause the spring and disk to yield, which wouldfail tov provide the necessary fixed part, while in back-wheeling from astationary position'fthe sprocket and hub come at once into engagementand, moving back together, move the balls on the fixed part, which riseon their cams and would jam if the relief-spring did not come intooperation under the powerful pressure so exerted.

What I claim is- 1. In a driving and braking mechanism, the combinationwith a hub having a flange on same, and a spindle on which the hub canrotate, of a free driving member, means carried by the hub for obtaininga lateral mor tion of such member to bring it into contact with theflange on the hub for driving purposes and meansfcarried by the spindlefor obtaining a similar lateral motion of such member to bring it alsoAinto contact with the flange on the hub for braking purposes.

2. In a driving and braking mechanism, a hub, a spindle on ,which samecan rotate, a free driving member at the extremity of said hub havinginterior cam-surfaces, a projection carried by the hub having a conicalface, a cage inside such free `driving member and movable over suchconical face, a ilange on the hub coperating with the free drivingmember and movable vparts in such cage cooperating with the conical faceand the camsurfaces of the free driving member whereby aforward movementimparted to the free driving member will produce a movement of the cageand impart a lateral movement to said free driving member to bring itinto frictional contact with'the flange on the hub.

8. In a driving and braking mechanism, a hub, a spindle on which samecan rotate, an

abutment carried by the spindle having camsurfaces, movable parts onsuch cam-surfaces, a free driving member between the hub and theabutment having interior cam-surfaces, a flange on the hub cooperatingwith the free driving member, a projection carried by the hub having aconical face, a cage inside such free driving member and movable oversuch conical face, movable parts in such cage, coperating with theconical face and the cam-surfaces of the free driving member whereby aforward movement imparted to the free driving member will produce aspiral movement of the cage and impart a lateral A movement to said freedriving member to bring it into frictional contact with the flange onthe hub for driving while a backward movement of the free driving membercauses the movable parts on the abutment to rise up the cam-surfaces andalso force the free drivthe hub for braking.

driving member also causing them to roll on the cam-surfaces of suchmember the combined movement producing a spiral movement of the freedriving member in the direction of the hub with which it then engages.

5. In a driving and braking mechanism,a

hub, a flange on same, a spindle on which same can rotate, a disk-shapedabutment on the spindle having cam-surfaces and rolling parts thereon, afree driving member between the hub and the abutment having a series ofcam-surfaces in the interior of same, a proj ection carried by the hubhaving a conical face,

and rolling parts between such conical facev and the cam-surfaces of thefree driving member whereby a forward movement imparted to the freedrivingr member will also act to produce in it a spiral movement tobring it into frictional contact with the ilange on the hub for driving,a backward movement of the free driving member causing the rolling partson the abutment to rise up the cam-surfaces thereof and also force thefree driving member frictionally against the flange on the hub forbraking.

6. In a driving and braking mechanism, andin combination, a hub havingan expanded extension 15, a projection 14, a conical ring carriedthereby, a spindle on which such hub can rotate, a disk-shaped abutmenton the spindle having a series of cam-surfaces thereon, a rolling partfor each cam-surface, a free driving member between the abutment and thehub having a series of cam-surfaces in the interior of same, ballsbetween the camsnrfaces of such free member and the conical ring, aball-bearing for such free member, a conical sleeve 19 adapted to slideon the projection 14 and forming part of such bearing, and a spring forpressing such sleeve 19 forwardly so that adjustment of the bearings isconstantly maintained. l

7. In a driving and braking mechanism, the combination with a hub, aflange on same, a spindle on which said hub can rotate, an abutment onthe spindle having cam-surfaces and rolling parts thereon and a freedriving member between the hub and its abutment having cam-surfacesinside same, of a projection 14 on said hub, having a conical surface13, a loose cage between such surface and the free driving member, ballscarried by such cage adapted to contact with the conical surface 13 andthe cam-surfaces of the free driving-member and a coil-spring engagingwith the free member and with the cage whereby IOO IIO

the latter will be kept in a position so that; the my hand in bhepresence of two subscribing balls will be forced into the narroWestpoint witnesses. between the cams on the free driving mem- 1 ber and theconical surface so that; the free ERNST GUSTAV HOFFMANN' 5 drivingmember is always ready for forward Witnesses:

driving. ALLEN PARRY JONES,

In testimony whereof I have hereunto set'l HERBERT ARTHUR MARSHALL.

